This invention relates generally to semiconductor structures and devices and to methods for their fabrication, and more specifically, to semiconductor structures, devices, and integrated circuits capable of optical communication.
Semiconductor devices often include multiple layers of conductive, insulating, and semiconductive layers. Often, the desirable properties of such layers improve with the crystallinity of the layer. For example, the electron mobility and band gap of semiconductive layers improves as the crystallinity of the layer increases. Similarly, the free electron concentration of conductive layers and the electron charge displacement and electron energy recoverability of insulative or dielectric films improves as the crystallinity of these layers increases.
For many years, attempts have been made to grow various monolithic thin films on a foreign substrate such as silicon (Si). To achieve optimal characteristics of the various monolithic layers, however, a monocrystalline film of high crystalline quality is desired. Attempts have been made, for example, to grow various monocrystalline layers on a substrate such as germanium, silicon, and various insulators. These attempts have generally been unsuccessful because lattice mismatches between the host crystal and the grown crystal have caused the resulting layer of monocrystalline material to be of low crystalline quality.
If a large area thin film of high quality monocrystalline material was available at low cost, a variety of semiconductor devices could advantageously be fabricated in or of that film. In addition, if a thin film of high quality monocrystalline material could be realized beginning with a bulk wafer such as a silicon wafer, an integrated device structure such as communication circuits could be achieved that took advantage of the best properties of both the silicon and the high quality monocrystalline material.
Correspondingly, communication circuits, networks and devices are being required to handle ever-increasing number of application such as desktop video-conferencing, interactive TV, supercomputer interconnection, and telemedicine applications. The increasing number of users who will use these applications may require ultra-high total network throughputs ranging from several hundreds of gigabits per second (Gb/s) to perhaps even several terabits per second (Tb/s). To meet these requirements, advanced optical communications networks and devices will need to be capable of transmitting, receiving, multiplexing, and de-multiplexing at increased speeds and baud rates.
Fiber optic networks and devices can operate at speeds up to 2.5 Gb/s making fiber optic devices one of the best solutions to the increasing demand for speed and bandwidth. Speed and bandwidth of fiber optic semiconductor structures, specifically transmitters and receivers, can be limited by the loss of signal from coupling between the fiber and the structure. The loss of signal can be from the light source no longer being optimally focused on the fiber end. Wide varieties of lenses are available for laser to fiber couplers to aid in preventing the signal attenuation. Aspheric, achromat, anplano-convex, and biconvex are to name but a few however, the optical throughput in a lens system remains constricted due to their fixed focal lengths and variable locations of the fiber end.
Accordingly, a need exists for a semiconductor structure that provides a high quality monocrystalline film or layer suitable for fabricating optical components such as those listed above. In other words, there is a need for providing the formation of a monocrystalline substrate that is compliant with a high quality monocrystalline material layer so that true two-dimensional growth can be achieved for the formation of quality semiconductor structures, devices and integrated circuits having grown monocrystalline film having the same crystal orientation as an underlying substrate. This monocrystalline material layer may be comprised of a semiconductor material, a compound semiconductor material, and other types of material such as metals and non-metals. Further, there is a need for optical components to be created and integrated together utilizing such a semiconductor structure.